Russian rescuers were scrambling to save 13 workers trapped inside a giant gold mine near the Chinese border for more than 48 hours, with officials warning of a "difficult situation."

Russia has said the miners have been stuck since Monday after a rockslide covered them in rubble at the Pioneer mine in the Far Eastern Amur region.

The mine is one of the largest in the world and one of the most productive in Russia.

"The situation at the mine is difficult but all the measures will be taken to find and save people," the deputy head of Russia's emergency ministry, Anatoly Suprunovsky, said.

Specialists were working "round the clock", removing more than "3,100 cubic meters of soil" and pumping out "more than 1,200 cubic meters of water", he added.

Authorities said it could take between up to three days to drill deep enough to get to the miners, thought to be around 125 meters (more than 400 feet) underground.

Regional governor Vasily Orlov has said there has been no contact with the miners but officials believe they are alive.

Orlov said "the most experienced" experts from Siberia's Kuzbas mining region had arrived Wednesday to help the rescue operation. They joined a team of more than 100 other rescuers already working at the site.

The emergency ministry published a video of rescuers trudging through a light layer of snow in the giant remote mine — wearing white helmets with headlamps.

Officials have already opened an investigation for a suspected breach of safety rules. Lax safety measures have often led to deadly accidents in Russian mines and factories.

The Kremlin said Tuesday President Vladimir Putin "gave the order to take all necessary measures to save the miners".

Miners believed alive

Authorities have posted aerial photographs showing the scale of the rescue mission in the giant remote mine, which is surrounded by deserted steppes.

Orlov said earlier Wednesday that rescue teams had began drilling a hole to try to reach the miners.

"Even if the passage does not lead to people it will be possible to lower a camera into it to assess the situation and lay communication lines," he explained.

Later, he said a second well was being drilled into the shaft of the mine to "more accurately assess the situation inside". Medics are waiting on standby at the top of the mine, he added.

Orlov said the trapped miners were workers from other regions.

The state-owned Izvestia newspaper quoted a relative of one of the miners who said she was from Sibay — a small town in the Urals region of Bashkortostan region.

"From our town, from Sibay, there are four people there," the woman, named as Rimma Akhmadeyeeva told the paper.

"The town is small, everyone knows each other. My phone is exploding and on social media (people are) writing, supporting (us)," she added.

"We still hope for a good end, that they are alive."

On Tuesday, Russia's Emergencies Minister Alexander Kurenkov said: "People who are under the rubble know that people are coming to help them."

The rescuers were trying to work at "maximum speed" to get through "100-200 meters" every two hours.

Accidents at mines are relatively common in Russia. In 2021, an accident at a coal mine in Siberia claimed the lives of 40 miners.